Tattooing is a well-known and wide spread practice of marking or decorating human skin that is accomplished by injecting colored pigment into small deep holes made in the skin. Tattoos may have a wide range of colors and are relatively permanent. At estimated 25 million people in the United States have at least one such permanent tattoo, and with the current popularity of “body art”, estimates are that over 250,000 women are being tattooed each year. The average age of people procuring a tattoo is approximately 18 years. These tattoos acquired in youth often become an embarrassment in later life as, in general, tattoos are not well received by the public and often create a barrier to employment or social acceptance. There is, therefore, a significant demand for the removal of tattoos.
Tattoo removal, however, is not easily accomplished. In tattooing, pigments are injected into the dermis. This is the layer of skin that lies immediately beneath the approximately one mm thick epidermis, which is the dead, external surface layer of the skin. The injected pigments initially tend to aggregate in the upper dermis, close to the epidermis. Physical removal of tattoos, therefore, requires abrading away the entire epidermis immediately above the tattoo pigment. This may be a painful process and may leave the subject with significant scarring. Over time, the tattoo pigments may become encapsulated in fibroblasts and migrate deeper into the dermis so that older tattoos, while a little duller, are even more difficult to remove by abrasion.
With the advent of high power lasers, an alternative, non-abrading method of removing tattoos that relies on thermal photoablation has become possible. In tattoo removal based on thermal photoablation, the laser wavelength is chosen so that the tattoo pigment absorbs the laser light more readily than the surrounding skin does. The laser pulses are then made powerful enough so that the pigment heats up sufficiently to thermally photoablate, i.e., to dissociate into small fragments. These fragments are typically no longer colored and may be also transported out of the dermis by macrophages or diffusion.
Tattoo pigments, however, cover a range of colors, including black, white, blue, red, green, and others. Dark blue-black amateur and professional tattoos usually contain amorphous carbon, graphite, India ink, and organo-metallic dyes. There is, therefore, no one laser most suitable for tattoo removal by thermal photoablation.
Tattoo removal is, therefore, currently accomplished using a variety of lasers to induce thermal photo-ablation including, but not limited to, Q-switched Nd:Yag lasers typically operating at 1064 nanometer (nm) or 532 nm, with 5-20 nanosecond (nsec) pulse duration, Q-switched Alexandrite lasers typically operating at 755 nm, with 100 nsec pulse duration, and Q-switched Ruby lasers typically operating at 694 nm, with 20-40 nsec pulse duration.
All these lasers, collectively known as nsec-type lasers, may be employed in a similar manner to remove tattoos. Typically, a cream to numb the skin is applied to the patient prior to the treatment to reduce the level of pain felt during the treatment. Short pulses of the laser light, typically of the order of 5 to 100 nsec, are then directed through the surface of the subject's skin and are absorbed by the tattoo pigment. The light breaks the pigment into particles by thermal photoablation. The particles are small enough to be absorbed by the body.
The principal sources of trauma in the nsec laser treatment of tattoos are the heating of the skin, which causes damage similar to a second-degree burn, and the formation of highly localized shock waves in the dermis that cause undesirable tissue damage. After the treatment, the body's scavenger cells remove the particles of pigment from the treated pigmented areas. The skin and tissue damage then heals over the next several weeks. More then one treatment is usually necessary to remove the entire tattoo. Some scarring or color variations are likely to remain. Healing time varies depending upon the size and depth of the tattoo, the procedure used and the patient's healing process.
All the current laser procedures for tattoo removal are painful, expensive, rarely 100% effective, may leave permanent scarring and typically require multiple treatments spread over a period of time.
What is needed is a tattoo removal system and method that is more effective than the existing methods, does not leave permanent scarring and is preferably not painful and can be accomplished in a single treatment.